Virtual Disk X is mounted, and it is shared via Windows File Sharing Service.
The back-end server is a Linux system.

Other Windows Machine (XP or 7) is accessing the shared folder and copying "MyDoc.doc" to it.

The problem is appearing when a DRM (Digital Right Management) application is trying to draw its icon upon the existing icon of "MyDoc.doc" (like TortoiseSVN draws its icon when you create a repository).

The error is "An unhandled win32 exception occurred in explorer [PID]".
After the error, Explorer restarts. And if we browse to the shared folder we can see "MyDoc.doc" with the overlay icon (it was drawn anyway, even after the error).

And no exceptions are raising in my application.
I have no idea where to look in my code in order to find any clue to solve the issue.

Temporarily, I have solved the problem by disabling the DRM's shell extension.

By the way, the Mapper sample has no such issues with the DRM.
That's why I am sure that my code implementation is causing such weird behavior of DRM's Shell Extension.

I would suggest you to contact DRM application's vendor and ask them to check why their extension crashes. There's nothing we could do on our site. It can be that you are handling some request incorrectly or not handling it, but this is what only DRM stuff authors can tell you.

Try to use Process Monitor from sysinternals.com. Mark in the menu "Filter"->"Enable advanced output" and maybe set some filter rules (like "Path"->"begins with"->"X:" and/or "Process name"->"is"->"Explorer.exe"). Then reproduce the problem and see what the latest requests were made by Explorer.